Improvement in draw-bridges



J. L. PIPER.

Improvement in Draw-Bridges.

No. 132,410. Patentedocr. 22,1872.

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` UNITED S'rA'rEs JOIzlN L. PIPER, OF PITTSB URG, PENNSYLVANIA.

IMPROVEMENT IN DRAW-BRIDGES.

Specification forming part of Letters Patent N o. 132,410, dated October 22, 1872.

To all whom fit may concern:

Be it known that I, JOHN L. PIPER, of Pittsburg, in the county oi' Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Draw-Bridges; and I do lhereby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawing making part of this speciiicatiom in Which- Figure lis a top or plan view of the system of bearing-rollers which I employ, and Fig. 2 is a transverse vertical section through the base-plate, cap-plate, and interposed devices.

Like letters oi' reference indicate like parts in each.

In the construction of railroad draw-bridges of long span great difficulty has been eX- perienced in providing rolling devices which would always keep in place, and which were oi' sufficient strength to carry the immense weight of the draw or swinging part of the bridge. Spherical balls have been found unsatisfactory, since the requisite strength cannot be secured Without too great an increase Oonical rollers have been tried, but they will Work satisfactorily only so long as the length of bearing-surface is not greater than the longest diameter oi' the roller. When this ratio ceases to exist it has been found that the roller is liable to iiy around till its axial line is a chord to the periphery of the track. Rollers so limited in length are, in very heavy bridges, insufcient to carry the load safely and permanently. By my improvement I lengthen the rollers as much as may be desired to enable them to withstand the crushing strain to Which they are subject Without necessarily increasing to any considerable extent their diameters. To prevent them from turning endwise I mount them in bearings at each end, the journals playing in a rotatory frame, and make the outer. journal with an end bearing, and, in order to keep the bearings permanently oiled, I carry an annular llange upward from the base-plate, so

` that the base-plate itself constitutes an oilcup. This being filled with oil, all the bearing-surfaces Will be kept permanently oiled.

To enable others skilled in the art to make and use my improvement, I will proceed to describe its construction and tion.

The base-plate B is mounted on top of the central pier in the usual Way. From its center rises the guiding-post B', Which is the ceutral pivoting-point of the bridge. The baseplate B is preferably of circular form, and is made of any desired diameter, varying, chielly, according to the length of the rollers to be used therewith. From its outer periphery rises an annular iiange, b, the upper edge of which comes, preferably, up to, or nearly to, the lower face of the cap-plate A, and at least up to the level of the end bearing of the rollers. This gives, in eEect, a cup-shaped base, and such base constitutes an oil-cup to the devices inside. Bein filled With oil, it keeps all the bearings properly and permanently lubricated. Dust and dirt are excluded by thecup A. Inside the cup-shaped base B I place a cast-metal frame, D, which consists of an inner hub, d, Which passes over the post B', radial arms d', and an outer rim, d, the Whole arranged to rotate freely inside the cupshaped base B. This feature is an important one-namely, a rigid and strong connection between the hub and outer rim, so that both may rotate in all cases with the same rapidity, and keep the conical rollers, presently to be described, in the radial line oi' the frame. For bearing -rollers I make a series of rollers, c, each of the form of a cone, or the frustum oi' a cone. I prefer to forge them of cast-steel, and finish them up by turning. Each one has on its larger end an outer journal, c', Which plays in a liole bored into the inner face of the rim d, so as to have an end bearing therein. The journal c on the opposite or smaller end plays in any suitable bearing in the hub cl, as illustrated in Figs. l and 2, such as will keep the roller in a radial position with reference to the frame, and prevent its turning endwise. The rollers can then be made as long as may be desired. For a rolling surface on Which they may operate I make, on the bottom of the base B, an annular inclined tread or track, g, of a slope corresponding to the taper of the rollers, and as broad as the rollers are long. On the under side of the cap A I make a similar counter-track, g. Both these tracks I prefer to make of forged steel,

mode of opera- 2 reame planed to the proper slope, though other suitable material in this, as in the other parts, may be employed. AThe cap A rests by its counter-head g on the rollers c, which are denarily in use for such purposes, both on the end of the journals c and at the bottoms or inner ends of the bearings in which they work, and by leaving a little space between the larger ends of the rollers and the inner face of the rim d, so that as the end bearings wear away the rollers may work outwardly` in a radial line, the devices described will withstand long and constant Wear without danger of breakage7 (if properly proportioned,) and require renewal only at long intervals. I am thus enabled, by simply enlarging the base, cap, and tread, and lengthening the rollers, to provide for carrying safely and permanently a draw-bridge, or other swinging superstructure, which would be too heavy for the spherical balls, rollers, or wheels heretofore in use.

The same construction is also applicable to railroad turn-tables, where it may be used with great advantage, and such application I include in my invention; and in such and other sinoerstructures where the superincumbent weight is comparatively small, the length of the rollers may be lessened. even till their lengths are less than their largest diameters.

What l claim as my invention, and desire to secure by Letters Patent, is

In draw-bridges, or other swinging superstructures, arotating frame, D, consisting of inner and outer rings d d" connected rigidly together by rigid arms d', in combination with inclined tracks g g and a series of conical rollers, c, each roller being journaled at its ends, and the outerjournal c of each having an end bearing in the ring d, substantially as described.

In testimony whereof I, the said JOHN L. PIPER, have hereunto set my hand.

` JOHN L. PIPER. Witnesses:

A. S. NICHOLSON, J AMES I. KAY. 

